Variable square-wave drive device

Abstract

A variable square-wave drive device for controlling square waves using feedback- and bias-control methods. The variable square-wave drive device includes an oscillator for generating a clock pulse; a frequency-divider / duty controller for frequency-dividing the clock pulse received from the oscillator to generate a clock signal and a square-wave signal; a drive for amplifying the square-wave signal received from the frequency-divider / duty controller according to a bias voltage, generating first and second square-wave signals having opposite phases, and outputting the first and second square-wave signals as a square-wave drive signal; a feedback controller for comparing a predetermined voltage variable determined by a user with the bias voltage of the drive to generate a comparison result signal; a switching controller for generating a switching signal upon receiving the comparison result signal from the feedback controller; and a bias voltage regulator for charging / discharging the input voltage according to the switching signal received from the switching controller so that it can adjust the bias voltage of the drive.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a variable square-wave drive device for use in camera modules such as an HHP (Hand Held Phone), and more particularly to a variable square-wave drive device for controlling square waves using a feedback- or bias-control method to vary the square waves, such that it can correctly control a curvature of an LL (Liquid Lens), and can more precisely and stably control focus and zoom functions of a camera module. [0003] 2. Description of the Related Art [0004] Typically, two different liquids are contained in a transparent body of an LL, and individual curvatures of the liquids can be adjusted by a driving voltage, such that it is well known in the art that the focus and zoom functions of the camera module can be controlled without using additional mechanical mechanisms. [0005] Optical devices using liquid crystal lens have been disclosed in U.S. Pat. Nos. 4,190,330 and 6,433,770, which ar...

AI Technical Summary

Benefits of technology

The present invention provides a variable square-wave drive device for controlling square waves to vary the curvature of a Liquid Lens and stably control focus and zoom functions of a camera module. The device includes a power-supply unit, an oscillator, a frequency-divider / duty controller, a drive, a feedback controller, a switching controller, and a bias voltage regulator. The device can control the focus and zoom functions of a camera module using a pair of square-wave drive signals with opposite phases. The power-supply unit can be powered on or off by an input power-saving signal to reduce power consumption. The switching controller can perform an AND operation between the comparison result signal and the clock signal to generate a switching signal. The switching controller can be synchronized with the clock signal of the frequency-divider / duty controller for more accurate performance.

Problems solved by technology

However, the aforementioned conventional liquid crystal lens drive circuit cannot control a curvature of the LL, such that it is also unable to perform a focus control function capable of being carried out using such a curvature control function.

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